An epoxy resin has been used for materials such as adhesives, molding materials, and coating materials and also has been widely used in the electrical and electronic fields of semiconductor sealing materials or insulating materials for a printed circuit board in terms that an obtained cured product has excellent heat resistance or moisture resistance.
In the electrical and electronic fields, a power semiconductor typified by an automotive power module is an important technology that holds the key to energy savings in electrical and electronic devices. With further enlargement of the current, miniaturization, and an increase in efficiency of the power semiconductor, transition from a silicon (Si) semiconductor of the related art to a silicon carbide (SiC) semiconductor has proceeded. The advantage of the SiC semiconductor is that the semiconductor can be operated under a higher temperature condition, and therefore higher heat resistance is required for a semiconductor sealing material more than before. In addition, it is important for the required performance of a resin for a semiconductor sealing material to exhibit high flame retardancy even when a halogen-based flame retardant is not used and to be provided with a filler which has a low viscosity and excellent fluidity and can be highly filled, and a resin material having all these properties has been demanded.
As the resin material compatible with these various required characteristics, for example, an epoxy resin containing an epoxy compound represented by the following structural formula is known (see PTL 1).

In the formula, G represents a glycidyl group.
Such an epoxy resin exhibits excellent heat resistance in terms of a cured product thereof, but flame retardancy is not sufficient and melt viscosity is high.